This undated file photo is believed to show Ibrahim Hassan Asiri, the Al… (Saudi Arabia Ministry of…)
WASHINGTON — The FBI is analyzing a sophisticated explosive device, similar to the underwear bomb used in an attempt to blow up a passenger jet over Detroit in 2009, that U.S. officials believe was built by Al Qaeda's affiliate in Yemen in an effort to target Western aircraft.
U.S. officials said Monday that no one was captured by U.S. agencies as part of the operation. The officials emphasized that they found no sign of an active plot to use the new bomb design against U.S. aviation or U.S.-bound jetliners.
The device was given to the CIA by a government outside Yemen, officials said. The White House said President Obama was informed of the discovery in April by John Brennan, his top counter-terrorism advisor, and was assured it "did not pose a threat to the public."
Despite the timing, U.S. officials said they did not believe the device was to be used to mark the first anniversary last week of the killing of Osama bin Laden, or the start ofU.S. military tribunal proceedings against five men accused of orchestrating the terrorist attacks of Sept. 11, 2001.
"At no time was this a viable plot," said a U.S. official who was not authorized to be quoted discussing the matter.
Instead, U.S. officials said, the discovery demonstrates Al Qaeda's continued interest in designing a bomb that can be smuggled through ever-tighter airport security, including body imaging machines, to bring down a passenger jet.
The device is "very similar" to bombs previously designed by Al Qaeda in the Arabian Peninsula, which is based in Yemen, in attempted attacks "against aircraft and for targeted assassinations," the FBI said in a statement.
The device "has the hallmarks" of bombs used in a failed attempt to kill a senior Saudi security official, Muhammad bin Nayef, in August 2009, and in the failed plot to blow up a Northwest Airlines jetliner over Detroit on Christmas Day 2009, said a second U.S. official who would not be quoted by name discussing national security information.
But the latest bomb is an improved version, the official added, with a better detonation system.
"It is clear that AQAP is revamping its bomb techniques to try to avoid the causes of the failure of the 2009 device" over Detroit, the official said.
After an initial examination, the FBI concluded the device was probably built by Ibrahim Hassan Asiri, arguably the terrorist network's most infamous and ambitious bomb maker. Asiri is known for using pentaerythritol tetranitrate, or PETN, and hiding bombs in imaginative ways.
Asiri's bombs are a source of intense concern to Western security officials. PETN gives off relatively little vapor, making it more difficult to detect by bomb-sniffing dogs. Since it can be detonated without metal parts, it may pass through metal detectors without raising alarms.
Asiri's fingerprint was found on the bomb hidden in the underwear of Umar Farouk Abdulmutallab in the Detroit case. The bomb in his pants fizzled but did not explode.
In February, a U.S. federal judge sentenced Abdulmutallab to life in prison without parole after he was convicted of attempted use of a weapon of mass destruction, attempted murder of 289 people and other crimes.
FBI bomb analysts believe Asiri also built bombs that were hidden in printer cartridges in October 2010 and shipped as air freight on cargo jets headed for the U.S. That plot was thwarted with the help of Saudi intelligence.
Sen. Dianne Feinstein (D-Calif.), chairwoman of the Senate Intelligence Committee, said Monday that the latest device was "of new design and very difficult to detect" by a metal detector.
National security officials said the device showed that Al Qaeda's affiliate in Yemen remained determined to attack the United States and its allies.
"The device and the plot are consistent with what we know about AQAP's plans, intentions and capabilities," said a U.S. official who spoke on condition of anonymity when discussing classified information. "They remain committed to striking targets in Yemen, Saudi Arabia, the homeland, and Europe."
The official added that Al Qaeda was "probably feeling pressure … to avenge the deaths" of Bin Laden and Anwar Awlaki, an American-born member of Al Qaeda who was targeted and killed by a U.S. drone strike in Yemen last fall.
The White House, which was accused by critics of trying to politicize the anniversary of Bin Laden's death to help the president's reelection campaign, rushed to reassure the public.
Caitlin Hayden, deputy spokeswoman for the National Security Council, said in a statement:
"While the president was assured that the device did not pose a threat to the public, he directed the Department of Homeland Security and law enforcement and intelligence agencies to take whatever steps necessary to guard against this type of attack."